The present invention relates generally to spray nozzle assemblies, and more particularly, to external mix air atomizing spray nozzle assemblies in which a discharging liquid flow stream is atomized and formed into the desired spray pattern by pressurized air externally of the liquid discharge orifice.
External mix air atomizing spray nozzles are known for their ability to control liquid particle size and spray distribution by pressurized air, substantially independent of liquid flow rate. Such spray nozzle assemblies typically include a liquid spray tip through which the liquid flow stream is directed and an air cap mounted in surrounding relation to the liquid spray tip for directing pressurized air streams that interact with the liquid flow stream discharging from the spray tip to further break down the liquid into particles and to direct the particles into the desired spray pattern. Such air assisted spray nozzles commonly are used in industry for directing highly viscous coatings onto various products.
By virtue of the turbulence that can be created as a result of the intermixing pressurized liquid and air streams discharging from the spray nozzle assembly, randomly directed particles can contact and accumulate on externally exposed faces of the liquid spray tip and air cap, which can quickly impede the discharge of the liquid and air flow streams and prevent the necessary uniform application of the coating materials. In some cases, such accumulations can occur within as short a period as 15 minutes of operation, necessitating frequent shut-down of the production line in order to clean the nozzle assemblies. Repeated interruption in the spray operation significantly affects efficiency of the processing system.
It is an object of the present invention to provide an improved air assisted spray nozzle assembly adapted for more efficiently spraying highly viscous materials.
Another object is to provide a spray nozzle assembly as characterized above which has a design which substantially reduces or eliminates undesirable build up of sprayed material on externally exposed faces of the liquid spray tip and air cap.
A further object is to provide a spray nozzle assembly of the above kind that is relatively simple in construction and which lends itself to economical manufacture and usage.
Still another object is to provide a spray nozzle assembly of such type which can utilize standard conventional air caps.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: